Which antidote is used for cyanide toxicity?

Sodium thiosulfate is the antidote used for cyanide toxicity due to its role in detoxifying cyanide in the body. Cyanide is a highly toxic chemical that inhibits cellular respiration by binding to cytochrome c oxidase, a crucial enzyme in the electron transport chain. This action disrupts the use of oxygen by tissues, leading to cellular hypoxia.

Sodium thiosulfate acts by providing a substrate for the enzyme rhodanese, which facilitates the conversion of cyanide into a less toxic compound, thiocyanate. Thiocyanate is then excreted by the kidneys, thereby helping to eliminate the cyanide from the body. This makes sodium thiosulfate a critical treatment option in cases of acute cyanide poisoning.

In contrast, calcium gluconate is not effective for cyanide toxicity; it is primarily used to treat hypocalcemia and certain conditions associated with calcium deficiency. Activated charcoal is useful for gastrointestinal decontamination of a variety of poisons but does not bind to cyanide effectively, limiting its use in cases of cyanide overdose. Vitamin K is used specifically for anticoagulant-related bleeding, particularly in cases of warfarin overdose, and has no role in cyanide poisoning.